The semiconductor industry has benefited from in-situ dry cleaning procedures made possible by exciting nitrogen trifluoride in a plasma and flowing the plasma effluents to clean interior surfaces of a substrate processing chamber. In-situ cleaning procedures avoid requiring chamber disassembly while still removing undesired substances such as silicon nitride, polycrystalline silicon, silicides and silicon dioxide. Removing these undesired substances before additional substrate processing may reduce defects and control electro-mechanical properties of processed layers.
A prior art chamber cleaning procedure is shown in FIG. 1 and begins when nitrogen trifluoride is flowed into a substrate processing chamber (operation 110). A plasma is formed from the nitrogen trifluoride (operation 115) to populate the processing chamber with reactive fragments of the nitrogen trifluoride. The plasma effluents are reacted with contaminants residing on interior surfaces of the chamber (operation 120). The reacted contaminants are then removed from the chamber through the chamber exhaust system (operation 125). The plasma may either reside in the chamber or outside (and upstream from) the chamber.
The relatively high cost of nitrogen trifluoride combined with speculation that the agent has a high global warming potential (GWP), are causing manufacturers to look for ways to use less NF3 per preventative maintenance procedure. Thus there is a need for new chamber cleaning agents which more effectively remove contaminants from the interior surfaces of substrate processing chambers and produce more eco-friendly exhaust gases.